1. Field of the Invention
The present invention relates to a heat exchanger.
2. Description of the Related Art
Conventionally, there is a heat exchanger to exchange heat between different fluids. For example, Japanese Laid-open Patent Publication No. 2003-262489 discloses a technology of a plate type heat exchanger including: a plurality of heat transmission plates which are stacked and have clearances between staked layers; and a partition wall interposed between the clearances, having inlets and outlets opened at edge portions of the heat transmission plates, and configured to form separate interlayer flow passages extending in the surface direction of the heat transmission plates. In this heat exchanger, the fluids having different temperatures alternately flow in the respective clearances adjacent to each other in the stacking direction while interposing the heat transmission plates, thereby exchanging heat via the heat transmission plates.
In the plate type heat exchanger disclosed in Japanese Laid-open Patent Publication No. 2003-262489, at least one of the interlayer flow passages functions a flow control flow passage having a flow control unit to control flow of the fluids that flows in from the inlets and flows out from the outlets. According to this plate type heat exchanger, heat exchange is performed by two kinds of fluids having different temperatures, such as a low-temperature reformed gas and a reform flue gas, via the heat transmission plates.
In the case where fluids to perform heat exchange is liquid in a heat exchanger, pressure loss is likely to fluctuate in response to temperature change. In the case of increasing a heat exchange amount in a heat exchanger in a high temperature range where kinetic viscosity of the liquid becomes low, it is advantageous to increase a contact area with the fluids by disposing a member such as a fin on a flow passage of the liquid. However, this kind of member increases the pressure loss in a low temperature range where kinetic viscosity of the liquid becomes high. When a flow speed of the liquid is reduced by such increase of the pressure loss, decrease of the heat exchange amount may be caused. In the heat exchanger that exchanges heat with the liquid, it is demanded to achieve both increase of the heat exchange amount and reduction of the pressure loss.
There is a need for providing a heat exchanger capable of achieving both increase of the heat exchange amount and reduction of the pressure loss.